A vehicle passing along a roadway, particularly a flat back van or sports utility vehicle, produces a partial vacuum and wake behind it. The partial vacuum causes dirt, rain and other airborne particles to be sucked into and enter the wake. Many of these particles are subsequently deposited on the rear of the vehicle, including the rear window.
In the past, a relatively flat deflector has been mounted on the back of the vehicle to divert air passing over the vehicle and direct it down over the rear of the vehicle. An example of this flat air deflector type system is shown in FIG. 5. The flat air deflector 70 includes an air deflector bar 72 supported at an angle by multiple stanchions 74 to deflect air downwardly over the rear of the vehicle 100. The stanchions 74 are connected to mounting bases 76 which are typically secured by screws 78 driven into the roof 106 of the vehicle 100. Such an attachment method damages the roof of the vehicle and often voids the new vehicle paint warranty and other warranties.
In addition, many previous deflectors such as the flat air deflector 70 depicted in FIG. 5 can create a certain amount of drag to the smooth flow of air over the vehicle. This drag is exacerbated by the relatively high profile of many prior deflectors and the abrupt manner in which the air is deflected downward.